Not sure where this is going, but maybe people have some ideas about what the deal is.

Beatrice herself had solved the epitaph and got the gold, or she was extremely wealthy already. (assuming all the deposits contained money, it was still just one-tenth of what the gold was worth of)

From what we watched in the Anime, the letters containing the bank cards already had the family seals on them, so Beatrice had already possessed the ring at least on Oct 3 th.

I suppose it should be Genji who held the ring after Kinzo's death (not that he wore it, but he kept it until Kinzo's death was announced and the next head of the family was chosen).

But actually he gave it to Beatrice while Krauss and Natsuhi did not know about it, since Beatrice was already the head of Ushiromiya family by solving the epitaph (Notice: solving the epitaph and taking away the gold were two different things.)

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The above reasoning also meant that none of the siblings would have already solved the epitaph as they must take the gold out immediately considering their financial situation.